Comparison of contrast-enhanced ultrasonography and contrast-enhanced computed tomography in the diagnosis of cystic renal cell carcinoma

Objective: To analyze the imaging features of contrast-enhanced ultrasonography (CEUS) on the cystic renal cell carcinoma (CRCC), and to assess the application value and clinical significance of CEUS in evaluating CRCC compared with conventional ultrasonography (US) and contrast-enhanced computed tomography (CECT). Methods: From April 2013 and July 2016, Thirty-two patients with 32 cystic lesions including 26 cases of CRCC and 6 cases of renal cysts who had undergone CEUS were retrospectively studied. All of the lesions were histopathologically proved. Evaluate diagnostic value of the conventional ultrasonography (US), CEUS and contrast-enhanced computed tomography (CECT) for CRCC. The conventional US was mainly used to observe the position, size, shape, border, echogenicity and blood supply of tumor. The CEUS mainly observes the enhancement performance of wall, septa and solid component of cystic lesions. The parameters include enhancement patterns, enhancement degree and pseudocapsule. The imaging findings and histopathological results were contrasted for statistically comparing capability of diagnosis on CRCC. Results: Among these 32 cystic lesions, 14 multilocular cystic renal cell carcinomas, 12 clear cell carcinomas and 6 renal cysts were confirmed through postoperative histopathologically. The accuracy rate, visualization rate of blood flow and visualization rate of pseudocapsule display rate of CRCC by the conventional US and CEUS are 62.3% (20/32), 31.2% (10/32), 12.5% (4/32) and 90.6% (29/32), 93.7% (30/32), 71.8% (23/32), respectively. CEUS can effectively reflect the blood supply of the lesions compared with the conventional US, so has higher diagnostic accuracy. The differences between them were statistically significant (P<0.01). By Receiver Operating Characteristic (ROC) curve analysis, this CECT (Area under the Curve (AUC)=0.776, P=0.038) and CECT (AUC=0.878, P=0.004), but not US (AUC=0.577, P=0.562) signature showed high accuracy in discriminating malignant from benign cystic lesions. The difference in diagnosis on CRCC by CEUS and CECT has no statistic significance (P>0.05). Conclusion: The CEUS can sensitively and effectively show the blood supply situation within CRCC. It is helpful to the diagnosis of CRCC, and has a certain clinical value. The Contrast-enhanced ultrasonography may play a similar role to contrast-enhanced computed tomography in the diagnosis of cystic renel cell carcinoma.